Perinatal transmission is responsible for over 98% of newly HIV infected children. The goal of decreasing perinatal transmission to 2% is the highest priority. A combination of strategies likely is necessary to achieve this goal. Antiretroviral therapy with potent new agents, administered to the mother and newborn, will be explored. In addition, HIV specific immune based therapy, including both active (vaccine) and passive (monoclonal antibody) will be delivered during pregnancy and/or the neonatal period. It is important to determine the optimal timing for these interventions; e.g. late pregnancy, intrapartum, early perinatal period. The eventual intervention should be stable, inexpensive and easy to deliver thus allowing application in developed and developing countries. A second goal is to determine whether the use of antiretroviral therapy and/or immune based therapy during the first weeks of life can modify the disease course in children. To determine efficacy in these patients, the specificity of viral load along with clinical endpoints must be determined. The continued investigation of combination therapy, including protease inhibitors, is important. As HIV infected children survive longer, Opportunistic Infections (OIs) will become even more prominent and effective prophylaxis and treatment of OIs must be defined. We have demonstrated our leadership as well as ability to enroll patients to clinical trials in all of these areas. Our consortium of 3 subunits is dedicated to the provision of treatment trials for lip, infected pregnant women, neonates, and children living throughout Northern California. The University of California, San Francisco serves the North Bay, and Children's Hospital Oakland the East Bay. The third subunit, the Bay Area Perinatal AIDS Center, is a referral facility for HIV infected pregnant women from throughout Northern California and is located at San Francisco General Hospital. All three subunits provide single site care for mothers and children and all have access to Clinical Research Centers (CRC). During the upcoming year, the three subunits propose continuing 141 patients and enrolling 80 new patients to ACTG protocols. Of these 80 new patients, 31 will be naive to the ACTG. 18 HIV infected children and 13 HIV infected pregnant women will enroll as new ACTG participants. Increased participation in Phase I trials will be facilitated by access to CRCs. UCSF investigators provide ACTG scientific leadership with expertise in immunology and a focus on trials involving perinatal transmission as well as Immune Based Therapy. Investigators at all subunits will continue to submit concept sheets and to serve as protocol chairs to advance the clinical investigation of the PACTG.